This invention relates to coaxial reel systems, and particularly to such systems used in the magnetic tape recording and reproducing arts.
In the magnetic tape transport art, it is occasionally desired to mount the tape supply and takeup reels coaxially, primarily to save space, and to make a more compact assembly, as for portability. In a portable transport for television recording, as of news events, for example, the camera operator usually carries the camera in a braced mount upon his shoulder, and the tape transport in a pack upon his back. Such a transport should therefore be no wider than the operator's shoulders and not much longer, to avoid encumbering the movements of the operator in crowds or in restricted spaces. The coaxial reel arrangement is of especial advantage in such use, if the television recording system is of the helical scan type, for then the tape enters the scanning zone at a different level that that at which it leaves, and the reels may be mounted coaxially at the same respective levels. Such is the environment for which the present reel system was devised.
In such a system, it is usually advantageous to have the inboard spindle, adjacent the tape deck, journalled for rotation upon a bearing means that extends from the deck or mounting element and passes entirely through the inboard spindle, while the outboard spindle is mounted on a shaft that passes in turn entirely through the bearing means. Thus both spindles may be driven by pulleys, belts and motors located entirely beneath the tape deck, or at least out of sight and protected from damage. The inboard spindle usually has a turntable flange to support the inboard reel, and key means mating with keyways in the hub opening of the inboard reel. Preferably the inboard reel at least is an "industry-standard" type, with three angularly equi-spaced keyways extending in an axial direction entirely through the reel hub. Usually in the art, the outboard reel is also of the "industry-standard" type and the outboard spindle also has key means mating with the keyways of both reels. The inboard reel, which is mounted first, of course can slide freely over the outboard spindle keys to its correct position on the inboard spindle. The problem is to prevent the outboard reel from doing the same thing. In other words, the task of the art is to find means which will act as turntable retaining and supporting means for the outboard reel, but will still allow free passage of the inboard reel.
Accordingly, it is an object of the present invention to provide a coaxial reel system in which the inboard reel passes freely over the outboard spindle, but the outboard reel does not.